热等静压粉末Ti_2AlNb合金的制备及电子束焊

Preparation and Electron Beam Welding of HIP Powder Metallurgy Ti-22Al-24Nb-0.5Mo Alloys

采用无坩埚感应熔炼超声气体雾化法制备了成分为Ti-22Al-24Nb-0.5Mo(原子分数,%)的预合金粉末,通过包套热等静压工艺制备了粉末Ti_2Al Nb合金。结果显示,粉末粒度显著影响粉末Ti_2Al Nb合金的孔隙分布。对制备的Ti_2Al Nb合金粉末环坯进行X射线探伤。结果显示,环坯无明显焊接气孔及夹杂缺陷。采用金相显微镜(OM)和扫描电镜(SEM)研究了粉末Ti_2Al Nb合金电子束焊接头显微组织,从熔合区到母材的组织为单相组织向双态组织过渡,熔合区和热影响区显微硬度略高于母材。

A Ti-22Al-24Nb-0.5Mo(at%)pre-alloyed powder was produced by gas atomization,and then fully dense powder metallurgy(PM)Ti_2Al Nb alloy was fabricated by a hot isostatic pressing(HIPing)route.powder size distribution obviously affects the porosity distribution of PM Ti_2Al Nb alloys.The weld porosity and inclusion are not found in the as-HIPed+HT Ti_2Al Nb rings to be electron beam welded according to the X-ray radiographic inspection.The microstructure of as-HIPed+HT Ti_2Al Nb compacts was characterized by optical microscopy(OM),scanning electron microscopy(SEM),and X-ray diffraction(XRD).From the fusion zone to the parent material,the microstructures change from the single phase(B2)to duplex(α_2+B2+O phase).The microhardness of fusion zone and heat affected zone is higher than that of parent material.